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Interfacial passivation of perovskite films is an effective way to further improve the power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). In this work, the combination of ionic liquid (IL) BMIMBF 4 and isopropanol (IPA) are used as green mixed anti-solvent. The existence of ionic liquids can delay the crystallization of perovskite and obtain dense perovskite films, because the non-volatile characteristics of BMIMBF 4 is left on the surface of perovskite, which is used for interfacial passivation. The perovskite film, which is prepared by mixed anti-solvent, can effectively reduce surface defects and significantly inhibit non-radiative recombination. Comparing with IPA as single anti-solvent, the PCE increased from 14.49% to 16.25%. In addition, the perovskite film with mixed anti-solvent still retains 76.8% of the initial efficiency after the unpacked PSCs are soaked in 100 mW/cm2 light for 20 days, and it retains 72.6% of the initial efficiency after 20 days of aging in an air atmosphere with 50∼60% relative humidity. The significant improvement of stability shows that the mixed green anti-solvent which combining BMIMBF 4 with IPA is an effective strategy for preparing stable PSCs by one-step method. [Display omitted] • Combining IL BMIMBF 4 with IPA are used as green mixed anti-solvent. • BMIMBF 4 left on the surface of perovskite is used for interfacial passivation. • Stability is significantly improved using the green mixed anti-solvent. [ABSTRACT FROM AUTHOR]

The facile approach combined the halide mixture of chloride and bromide anions with the exchange of short-chain ligand Phenethylamine (PEA) was used to prepare hybrid perovskite PEA-MAPbBr 3-x Cl x quantum dots (PEA-QDs-Cl), which realized blue emissive quantum dots light-emitting diode (QLED) with wider gamut of Commission Internationale de l'Eclairage (CIE) coordinates (Δx = −0.04, Δy = 0.03) than National Television Systems Committee (NTSC) TV color standard. Compared to pristine MAPbBr 3 quantum dots (pristine-QDs) prepared by conventional long-chain ligands, the size of PEA-QDs-Cl was manipulated from 9 nm to 3 nm characterized by HRTEM, emissive spectra were blue shifted from 528 nm to 469 nm measured by photoluminescence (PL). Meanwhile, time-resolved PL (TRPL) decay lifetimes of perovskite quantum dots doped with chloride anions (QDs-Cl) were improved from 10.3 ns to 13.9 ns, because short-chain ligands were introduced to passivate defects on the surface of QDs-Cl. Furthermore, XPS results showed that the chloride content was decreased from 34.7% to 33.7% through chloride vacancies on the surface of QDs-Cl were passivated by PEA. [Display omitted] • Perovskite quantum dots prepared by halide mixture of chloride and bromide anions. • Introducing short-chain ligands to passivate the defects on the surface of QDs-Cl. • Sizes of QDs-Cl were manipulated from 9 nm to 3 nm by anion exchange method. • PL shows color tunable emissive spectra were blue shifted from 528 nm to 469 nm. • Blue emissive perovskite QLEDs with wider gamut of CIE coordinates than NTSC. [ABSTRACT FROM AUTHOR]